Q&A - P4 Science

[Jamesbond]

atutor2001:

Jamesbond:

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Can somebody help to answer (a)

In a hot air balloon, we use a poor conductor...hence hot air cannot escape making it to rise and float in air...etc is the explanation we give. Here they say it is a metal cup which is a good conductor....so my ds is confused....

Pl help...Thx.

This question is not testing on good/bad conductor of heat. The concept tested is \"hot air rises\" and will push anything upwards along the way.

Thank you atutor2001...

[Jamesbond]

Is television and mobile phone an example of light source....Some books say yes and some say no....Which is correct? Pl help.... :imdrowning:

[atutor2001]

Jamesbond:

Is television and mobile phone an example of light source....Some books say yes and some say no....Which is correct? Pl help.... :imdrowning:

In order to decide if something is a light source, ask the following questions :

(1) Does it emit light?
(2) Is the light reflected from some other sources?

If the answers is Yes, then No, that object is a light source. Therefore, television and mobile phone should be light source if they are switched on. (maybe that is why some books say yes and some say no - i.e. some books focusing on whether it is switched on and others assuming that it is in the \"on\" mode)

In P6, a new animal called \"energy source\" will be taught. This is different from \"light source\". TV and phone can emit light but they are not energy source because the energy comes from the \"power supply\" or \"battery\".

[Jamesbond]

atutor2001:

Jamesbond:

Is television and mobile phone an example of light source....Some books say yes and some say no....Which is correct? Pl help.... :imdrowning:

In order to decide if something is a light source, ask the following questions :

(1) Does it emit light?
(2) Is the light reflected from some other sources?

If the answers is Yes, then No, that object is a light source. Therefore, television and mobile phone should be light source if they are switched on. (maybe that is why some books say yes and some say no - i.e. some books focusing on whether it is switched on and others assuming that it is in the \"on\" mode)

In P6, a new animal called \"energy source\" will be taught. This is different from \"light source\". TV and phone can emit light but they are not energy source because the energy comes from the \"power supply\" or \"battery\".

Thanks a lot for clearing the doubts....

[AgonyMum]

Hi,question from Nanyang 2011 SA -

Which of the following human systems show an increase in activity when a person is running?
A muscular system
B respiratory system
C circulatory system

TIA!

[charsen]

AgonyMum:

Hi,question from Nanyang 2011 SA -

Which of the following human systems show an increase in activity when a person is running?
A muscular system
B respiratory system
C circulatory system

TIA!

All Three answers are correct.When the person is running,he inhales more air.
That means more food is needed from the digestive system to travel through the circulatory system.Then,more respiration happens at the lungs.Finally,the digested food would go to the muscular system to give energy for the person to run.
Charsen

[AgonyMum]

charsen:

AgonyMum:

Hi,question from Nanyang 2011 SA -

Which of the following human systems show an increase in activity when a person is running?
A muscular system
B respiratory system
C circulatory system

TIA!

All Three answers are correct.When the person is running,he inhales more air.
That means more food is needed from the digestive system to travel through the circulatory system.Then,more respiration happens at the lungs.Finally,the digested food would go to the muscular system to give energy for the person to run.
Charsen

Hi Charsen,
That was what my child wrote and I marked him correct.However, when I double-checked with the answer sheet provided, it was only circulatory and respiratory systems. Muscular system was not included. Do you know any reason why?
Thanks!

[charsen]

AgonyMum:

charsen:

[quote=\"AgonyMum\"]Hi,question from Nanyang 2011 SA -

Which of the following human systems show an increase in activity when a person is running?
A muscular system
B respiratory system
C circulatory system

TIA!

All Three answers are correct.When the person is running,he inhales more air.
That means more food is needed from the digestive system to travel through the circulatory system.Then,more respiration happens at the lungs.Finally,the digested food would go to the muscular system to give energy for the person to run.
Charsen

Hi Charsen,
That was what my child wrote and I marked him correct.However, when I double-checked with the answer sheet provided, it was only circulatory and respiratory systems. Muscular system was not included. Do you know any reason why?
Thanks![/quote]Hi
I am so sorry.The answer is circulator system and respiratory system.The muscular system remains in activity as they DID NOT mention whether the person runs faster as time passes.So,the person should be running at a constant speed,in which the muscular system functions at a constant rate.
Hope my explanation works.
Charsen

[AgonyMum]

Thanks Charsen

[atutor2001]

AgonyMum:

charsen:

[quote=\"AgonyMum\"]Hi,question from Nanyang 2011 SA -

Which of the following human systems show an increase in activity when a person is running?
A muscular system
B respiratory system
C circulatory system

TIA!

All Three answers are correct.When the person is running,he inhales more air.
That means more food is needed from the digestive system to travel through the circulatory system.Then,more respiration happens at the lungs.Finally,the digested food would go to the muscular system to give energy for the person to run.
Charsen

Hi Charsen,
That was what my child wrote and I marked him correct.However, when I double-checked with the answer sheet provided, it was only circulatory and respiratory systems. Muscular system was not included. Do you know any reason why?
Thanks![/quote]I think the answer sheet is wrong. When we run, our muscles contracts and relax at a faster rate than normal. The word \"activities\" should cover such movement of the muscles. Therefore, there is an increase in activities in the muscular system when we run (compared to when we are not running).